1. Field of the Invention
The present invention relates to a quick connector used to connect pipes to each other in piping for transporting a fluid such as fuel and oil for an automobile.
2. Description of the Related Art
As a conventional quick connector, a connector as shown, for example, in FIGS. 1 to 5 of JP 2005-535845 A has been known. For such a quick connector, in connecting a first coupling piece 1 and a second coupling piece 2 to each other, one coupling piece is pushed in until the coupling piece reaches a position (until the coupling pieces 1 and 2 reach a completely connected state) at which a locking member 3 of a holder arm 6 provided in the first coupling piece 1 engages with a ring-shaped peripheral flange part (locking member 4) provided on the second coupling piece 2. Thereby, the coupling pieces are prevented from coming off, and the coupling pieces are connected each other (refer to FIG. 4 of JP 2005-535845 A).
For the quick connector of this type, in the case where the pushed amount of coupling piece is insufficient, and the engagement of the locking member 3 and the locking member 4 is imperfect (hereinafter, in this specification, the state in which the pushed amount of one coupling or pipe is insufficient is referred to as an “incompletely connected state”), the locking member 3 of the coupling piece 1 cannot hold the ring-shaped locking member 4 of the coupling piece 2 to restrain its movement, so that the coupling pieces 1 and 2 may come off from each other. If fluid flows through the coupling pieces 1 and 2 which are in the incompletely connected state, the fluid leaks from a gap between the coupling pieces 1 and 2 and there is a possibility to damage the pipes, piping equipment and the like. In the worst case, the leaking fuel ignites and causes explosion, which may lead to a serious accident. Therefore, to check whether or not the coupling pieces have been engaged with each other in the state in which the coupling pieces are reliably prevented from coming off and have been pushed into completely until the locking members 3 and 4 engage with each other is very important for a person who uses a connector of this type (hereinafter, in this specification, the state in which one of the coupling pieces or pipes is pushed into the other completely is referred to as a “completely connected state”).
The conventional quick connector as described above, however, has problems described below. When the worker checks whether or not the coupling piece are pushed into each other sufficiently until the locking members 3 and 4 reach in the completely connected state, the worker must check the pushed amount by bringing his/her face close to the coupling piece to watch it carefully, or must try to check whether or not the coupling pieces are actually pulled away from each other by pulling the coupling piece by his/her hand. And such checking work is very troublesome. In particular, in the case where machines and parts are complicatedly laid out, or in the case where the coupling pieces are placed at a narrow place, the worker cannot bring his/her face close to the coupling piece, and also cannot reach his/her hand to the coupling piece. Therefore, in a narrow place, the worker needs to use a mirror to visually check the pushed amount of the coupling pieces, or use a fiber camera and a monitor to display the coupling pieces, and these works for checking the connected state is not easy. Also, since there is no much difference in the position of the locking member 3 of the above-described conventional quick connector regardless of whether the coupling pieces 1 and 2 are in the incompletely connected state or in the completely connected state, it is very difficult for workers wearing a hand protector such as leather gloves or cotton work gloves to exactly determine whether or not the coupling pieces are in the completely connected state by means of hand feeling only. In particular, in the case where a seal or an O-ring for improving the fluid tightness is provided at the location where the coupling pieces are engaged with each other, it becomes hard to connect the coupling pieces with each other. Therefore, the worker may mistake the engagement in the incompletely connected state for the completely connected state.